Adaptive reliability protocol

ABSTRACT

A device, method, and non-transitory computer readable medium that determine a reliability level for a communication network. A packet delivery ratio (PDR) is determined for a round period of the communication network operating at an adaptive reliability level based on a packet serial number (PSN). The communication network is controlled in a best effort mode, a reliable mode, or a switching mode based on the PDR.

BACKGROUND Technical Field

The present disclosure is directed to an adaptive reliability protocolfor wireless sensor networks.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Many of the proposed reliability quality of service (QoS) protocols forsensor networks are transport solutions as described by Y. Lyer, S.Gandham and S. Venkatesan, “STCP: a generic transport layer protocol forwireless sensor networks,” in the 14th IEEE International Conference onComputer Communications and Networks, San Diego, Calif., 2005, Y. Zhouand M. Lyu, “PORT: a price-oriented reliable transport protocol forwireless sensor network,” in the 16th IEEE International Symposium onSoftware Reliability Engineering (ISSRE), Chicago, Ill., 2005, S. Park,R. Vedantham, R. Sivakumar and I. Akyildiz, “A scalable approach forreliable downstream data delivery in wireless sensor networks,” in theACM MobiHoc '04, Roppongi, Japan, 2004, and V. Gungor and O. Akan, “DST:Delay sensitive transport in wireless sensor networks,” in the SeventhIEEE International Symposium on Computer Networks (ISCN), 2006, theentire contents of which are incorporated herein by reference. Transportlayer solutions are typically coupled with the sensor platforms, whichare integrated with existing routing/transport protocols.

Message Queuing Telemetry Transport for sensors networks (MQTTS-S) isdescribed in A. S. Stanford-Clark and H. L. Truong, “MQTT for sensornetworks (MQTT-S) protocol specification,” 2008, and U. Hunkeler, H. L.Truong and A. Stanford-Clark, “MQTT-S—A publish/subscribe protocol forWireless Sensor Networks,” in 3rd International Conference onCommunication Systems Software and Middleware and Workshops (COMSWARE2008), 2008, the entire contents of which are incorporated herein byreference. MQTT-S is an IBM publisher/subscriber (pub/sub) protocolinvented by Stanford-Clark and Hunkeler in 1999. MQTT-S is a simple andlightweight messaging protocol designed for constrained devices with lowbandwidth and for high-latency or unreliable networks. Consequently, dueto the lightweight properties, an extended version of the MQTT protocolwas proposed, which was suitable for wireless sensor networks. Theextended version of the MQTT protocol simplified the integration of thewireless sensor networks (WSNs) with the enterprise networks byextending the enterprise pub/sub middleware protocols into the WSNinfrastructure. In the architecture, the complexity of the sensordevices was reduced, and the pub/sub service included built-in brokersthat used the original MQTT protocol. The sensor devices used thecollection tree protocol (CTP), as described by O. Gnawali, R. Fonseca,K. Jamieson, D. Moss and P. Levis, “Collection tree protocol,” inProceedings of the 7th ACM Conference on Embedded Networked SensorSystems, 2009, the entire contents of which are incorporated herein byreference, as the underlying protocol which allows any device to senddata to the closest gateway. MQTT is also described in A. Stanford-Clarkand U. Hunkeler, “MQ Telemetry Transport (MQTT),” 1999. [Online].Available: http://mqtt.org. [Accessed 23 11 2014], the entire contentsof which are incorporated herein by reference.

At the application layer, three levels of reliability are provided byMQTT-S, which include: (1) best effort, where the publisher sends justonce whether successfully received or not; (2) retransmit until themessage is acknowledged, which may incur redundancy; and (3) assure noredundancy. Although QoS is provided, the MQTT-S reliability protocoldoes not adapt to network conditions since levels (2) and (3) functionwith fixed timeout at the publisher side. Further, the QoS control isimplemented at the publisher side, which in most cases is the side withthe battery-powered sensors, so network lifetime is reduced due to powerconsumption constraints.

Constrained Application Protocol (CoAP) was developed based on thefundamental Representational State Transfer (REST) architecture of theweb as described by Z. Shelby, B. Frank and D. Sturek, “ConstrainedApplication Protocol (CoAP),” IETF—The Internet Engineering Task Force,2012, the entire contents of which are incorporated herein by reference.CoAP was developed for constrained devices and networks, such as WSNs,to ease integration with internet applications while still meetingspecifications of constrained applications, such as Machine-to-Machineand home and building automation. CoAP includes two interaction models:the client/server model and the pub/sub model.

CoAP realizes a reliable QoS through two types of messages: (1) aconfirmable message where the publisher sends the message and waits foracknowledgement from the subscriber, and (2) a non-confirmable messagewhere the publisher does not wait for acknowledgement, e.g., besteffort. As with the MQTT-S model, the confirmable message also includesa fixed retransmission timeout. Likewise, CoAP does not take intoconsideration the network conditions to adapt the reliability protocol.In addition, the packet loss recovery control is also built at thepublisher side, which can have a significant effect on network lifetimedue to the limited battery life.

The adaptive retransmission timeout (RTO) protocol as described in E.Davis, A. Calveras and L. Demirkol, “Improving Packet DeliveryPerformance of Publish/Subscribe Protocols in Wireless Sensor Networks,”Sensors, vol. 13, no. 1, pp. 648-680, 2013, the entire contents of whichare incorporated herein by reference, aims at improving the staticreliable QoS proposed in the MQTT-S and CoAP. Likewise, the adaptive RTOis an application-based solution for WSN reliability, and the packetloss control also occurs on the publisher side. The adaptive RTOprotocol dynamically calculates the retransmission timeout based on thenetwork architecture and network conditions. The adaptive RTO protocolexploits the smooth round-trip time (SMRTT) to estimate networkconditions and calculate an updated RTO. A K parameter is used to ensurean accurate estimation of the RTO and has a significant effect on thereliability mechanism of the RTO protocol and is evaluated in single andmulti-hop topologies. Using adaptive methods, such as the RTO protocol,can improve reliability in constrained networks, such as WSNs. Forexample, the adaptive RTO method increases the packet delivery ratio(PDR) of MQTT-S by 76% and CoAP by 38% when using an appropriate valuefor the K parameter.

SUMMARY

In an exemplary embodiment, a device includes circuitry configured todetermine a reliability level for a communication network, determine apacket delivery ratio (PDR) for a round period of the communicationnetwork operating at an adaptive reliability level based on a packetserial number (PSN), and control the communication network in a besteffort mode, a reliable mode, or a switching mode based on the PDR.

In another exemplary embodiment, a method includes: determining, via aserver, a reliability level for a communication network; determining,via the server, a packet delivery ratio (PDR) for a round period of thecommunication network operating at an adaptive reliability level basedon a packet serial number (PSN); and controlling, via the server, thecommunication network in a best effort mode, a reliable mode, or aswitching mode based on the PDR.

In another exemplary embodiment, a non-transitory computer readablemedium having instructions stored therein that, when executed by one ormore processor, cause the one or more processors to perform a method ofadaptively controlling a reliability protocol, the method including:determining a reliability level for a communication network; determininga packet delivery ratio (PDR) for a round period of the communicationnetwork operating at an adaptive reliability level based on a packetserial number (PSN); and controlling the communication network in a besteffort mode, a reliable mode, or a switching mode based on the PDR.

The foregoing general description of the illustrative embodiments andthe following detailed description thereof are merely exemplary aspectsof the teachings of this disclosure, and are not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of this disclosure and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is a schematic diagram of an adaptive reliability protocolsystem, according to certain embodiments;

FIG. 2 is an exemplary flowchart of a reliability level determinationprocess, according to certain embodiments;

FIG. 3 is an exemplary illustration of a round period, according tocertain embodiments;

FIG. 4 is an exemplary flowchart of an adaptive reliability process,according to certain embodiments;

FIG. 5 is an exemplary flowchart of a round packet allocation process,according to certain embodiments;

FIG. 6 is an exemplary illustration of adaptive reliability operationregions, according to certain embodiments;

FIG. 7 is an illustration of a non-limiting example of base stationcircuitry, according to certain embodiments;

FIG. 8 is an exemplary schematic diagram of a data processing system,according to certain embodiments; and

FIG. 9 is an exemplary schematic diagram of a processor, according tocertain embodiments.

DETAILED DESCRIPTION

In the drawings, like reference numerals designate identical orcorresponding parts throughout the several views. Further, as usedherein, the words “a,” “an” and the like generally carry a meaning of“one or more,” unless stated otherwise. The drawings are generally drawnto scale unless specified otherwise or illustrating schematic structuresor flowcharts.

Furthermore, the terms “approximately,” “approximate,” “about,” andsimilar terms generally refer to ranges that include the identifiedvalue within a margin of 20%, 10%, or preferably 5%, and any valuestherebetween.

Aspects of this disclosure are directed to a system, device, and methodfor applying an adaptive quality of service (QoS) protocol to wirelesssensor networks (WSNs). In some implementations, an adaptive reliabilityprotocol system 100 includes a base station that receives sensor datafrom a communication network, such as a WSN, and determines a mode ofoperation for transmitting and/or receiving data packets based on apacket delivery ratio (PDR).

FIG. 1 is a schematic diagram of an adaptive reliability protocol system100, according to certain embodiments. The computer 110 represents atleast one computer 110 and acts as a client device that is connected toa database 108, a mobile device 112, a base station 102, and a wirelesssensor network (WSN) via a network 104. In some implementations, thecomputer 110 is used to view past and current PDRs, operation modes, andother specifications associated with transmission and reception ofsensor data packets. A user can also input a reliability level for theadaptive reliability protocol system 100 via an interface at thecomputer 110. In some implementations, the reliability level correspondsto minimum percentage of successfully delivered packets that may beguaranteed by the adaptive reliability protocol system 100. Detailsregarding the reliability level are discussed further herein.

The base station 102 represents one or more base stations connected tothe computer 110, the database 108, the mobile device 112, and the WSN114 via the network 104. According to certain embodiments, the basestation 102 can include processing circuitry that processes receivedsensor data from the WSN 114, determines a determines a reliabilitylevel for the adaptive reliability protocol system 100, determines thePDR for the system 100 by processing data packets having a predeterminedlength, and controls operation of the system 100 in a best effort modeor a reliability mode based on the PDR. By determining the PDR andassociated operation mode at the base station 102 having anapproximately unlimited energy source, a processing burden on the WSN114 can be reduced. Details regarding the processes performed by theprocessing circuitry of the base station 102 are discussed furtherherein.

The database 108 represents one or more databases connected to thecomputer 110, the base station 102, the WSN 114, and the mobile device112 via the network 104. In some implementations, historical dataassociated with the adaptive reliability protocol system 100, such aspreviously measured PDRs, reliability levels, and other performancemetrics can be stored in the database 108.

The WSN 114 represents one or more WSNs connected to the computer 110,the base station 102, the database, 108, and the mobile device 112 viathe network 104. In some implementations, the WSN can include one ormore spatially distributed sensor nodes that are configured to monitorphysical and/or environmental conditions. For example, sensors installedin an electrical system of a vehicle can be configured to sense voltage,current, temperature, and the like. In addition, weather sensors caninclude humidity sensors, temperature sensors, pressure sensors, windsensors, and the like. The sensors of the WSN 114 can transmit sensordata via the sensor nodes to a primary node that can transmit the sensordata to the base station 102 for further processing. In someimplementations, operating the WSN 114 at a predetermined reliabilitylevel involves processing overhead that may not be able to be met by theprocessing resources associated with the WSN 114. By applying anadaptive reliability protocol to the WSN 114, the processing overheadcan be reduced while still being able to achieve minimum PDRs. In someimplementations, processing circuitry associated with the WSN 114 can beconfigured to perform the processes described herein.

The mobile device 112 represents one or more mobile devices connected tothe computer 110, the base station 102, the WSN 114, and the database108 via the network 104. The network 104 represents one or morenetworks, such as the Internet, connecting the computer 110, the basestation 102, the database 108, the WSN 114, and the mobile device 112.The network 104 can also communicate via wireless networks such asWI-FI, BLUETOOTH, cellular networks including EDGE, 3G and 4G wirelesscellular systems, or any other wireless form of communication that isknown.

As would be understood by one of ordinary skill in the art, based on theteachings herein, the mobile device 112 or any other external devicecould also be used in the same manner as the computer 110 to input andview the reliability level and other performance specifications for theadaptive reliability protocol system 100. In addition, the computer 110and mobile device 112 can be referred to interchangeably throughout thedisclosure. Details regarding the processes performed by the adaptivereliability protocol system 100 are discussed further herein.

FIG. 2 is an exemplary flowchart of a reliability level determinationprocess 200, according to certain embodiments. In some implementations,the reliability level determination process 200 implements an adaptivereliability quality of service (ARQoS) protocol that can support threelevels ranging from a lowest reliability to a highest reliability. TheARQoS protocol can be designed to operate at a middleware or applicationlayer, independent from protocols associated with other underlyinglayers. Throughout the disclosure, the term reliability refers to howconsistently data packets transmitted from the WSN 114 are successfullyreceived by the base station 102. The reliability levels associated withthe ARQoS protocol can quantify how consistently the base station 102successfully receives the sensor data transmitted from the WSN 114.According to some aspects, the reliability levels include best effort,adaptive, and reliable levels where the best effort level corresponds toa lowest reliability, and a reliable level corresponds to a highestreliability.

At step S202, the processing circuitry of the base station 102determines a reliability level for the WSN 114 based on networkspecifications, application of the WSN 114, and the like. In someimplementations, the processing circuitry may determine the reliabilitylevel based on a rate of change of conditions monitored by the WSN 114.For example, environmental conditions monitored by a WSN 114, such asair pollution monitoring or water quality monitoring, may have a slowerrate of change than an application where the WSN 114 is used to detectbiological symptoms of a patient who has suffered from a serious medicalcondition, such as a stroke or a heart attack. In addition, theprocessing circuitry of the base station 102 can also determine thereliability level based on a level of criticality associated with theapplication of the WSN 114. For example, the level of criticality, whichcan also be referred to as time sensitivity, of a WSN 114 associatedwith monitoring conditions in a tactical military environment may behigher than a WSN 114 associated with monitoring environmentalconditions of a greenhouse. In addition, higher reliability levels canbe associated with higher levels of criticality for the WSN 114. Theprocessing circuitry of the base station 102 can determine thereliability level as a function of at least one of the rate of changeand the level of criticality of the application of the WSN 114.

The rates of change and levels of criticality associated with the WSN114 can be input via an interface at the computer 110 and/or mobiledevice 112 and stored in the database 108 of the adaptive reliabilityprotocol system 100. The reliability level for the WSN 114 can also bemanually input via the interface at the computer 110 and/or mobiledevice 112. The rates of change and/or levels of criticality can also bebased on learned trends from the WSN 114 and other WSNs associated withrelated applications. For example, the rate of change criticality levelassociated with a WSN that monitors air pollution can be based onlearned statistical data from other WSNs that monitor air pollution orother environmental factors. The processing circuitry of the basestation 102 can modify the rates of change and the criticality levelsassociated with each type of WSN stored in the database 108 based onlearned trends as sensor data is received and processed by the adaptivereliability protocol system 100. Also, the processing circuitry can alsouse other WSN statistics that are stored in the database 108 and/oraccessed via a web crawling process to determine how to modify thecriticality levels and rates of change associated with the WSN 114.

In one implementation, the processing circuitry assigns the WSN 114 toone of the three reliability levels based on at least one of the rate ofchange and the level of criticality of the application of the WSN 114.In addition, the processing circuitry also determines reliabilitypercentage values for the WSN 114 that quantify a minimum guaranteedlevel of accuracy with which the sensor data from the WSN 114 can besuccessfully transmitted from the WSN 114 to the base station 102. Inone implementation, the reliability percentage value is based on aweighted average of the rate of change of the sensors of the WSN 114 andthe criticality level of the WSN 114. For example, the weighted averageof the rate of change and the criticality level can correspond to apredetermined reliability percentage value for the WSN 114, which can beaccessed via look-up tables that are stored in the database 108. Theprocessing circuitry can also determine the reliability percentage valuebased on a manual input via an interface at the computer 110. Inaddition, the reliability percentage value can correspond to a minimumpacket delivery ratio (PDR) at which the adaptive reliability protocolsystem 100 operates.

For example, the best effort level may be a lowest reliability levelthat is associated with a reliability percentage value of 0%. Inaddition, the reliable level may be a highest reliability level that isassociated with a reliability percentage value of 100%. An adaptivereliability level is between the best effort and the reliable levels andcorresponds to a reliability percentage value from 1% to 99%. Forexample, the reliability percentage values can indicate a minimum packetdelivery ratio (PDR) for the WSN 114. For example, a 90% reliabilitypercentage value may correspond to a minimum allowed PDR of 90% for theWSN 114. In some embodiments, at session initiation, the processingcircuitry of the base station 102 transmits an initiation data packet tothe WSN 114 indicating the reliability percentage value andcorresponding reliability level. For example, one or more bits of theinitiation data packet can be allocated to indicating the reliabilitypercentage value.

At step S204, the processing circuitry of the base station 102determines whether the reliability level for the WSN 114 is adaptive.For example, the adaptive reliability level corresponds to a reliabilitypercentage value from 1% to 99%, which can be determined at step S202.If it is determined that the reliability level is adaptive, resulting ina “yes” at step S204, then step S212 is performed. Otherwise, if thereliability level is best effort or reliable, resulting in a “no” atstep S204, then step S206 is performed.

At step S212, if it is determined that the reliability level for the WSN114 is adaptive, an adaptive reliability process is performed. Theprocessing circuitry of the base station 102 determines the PDR for apredetermined amount of time, also referred to as a round period. Duringthe adaptive reliability process, the processing circuitry determines amode of operation for the WSN 114 by comparing the PDR to an upperthreshold and a lower threshold. Details regarding the adaptivereliability process are discussed further herein.

At step S206, if it is determined that the reliability level for the WSN114 is not adaptive, the processing circuitry determines whether thereliability level for the WSN 114 is reliable. For example, the reliablereliability level corresponds to a reliability percentage value 100%,which can be determined at step S202. If it is determined that thereliability level is reliable, resulting in a “yes” at step S206, thenstep S210 is performed. Otherwise, if the reliability level is besteffort, resulting in a “no” at step S206, then step S208 is performed.

At step S210, the reliable level is implemented at the WSN 114. In someimplementations, the reliable operations are employed for applicationsof the WSN 114 with a highest rate of change and/or highest criticalitylevel. For example, WSNs associated with tactical military operations,such as tracking a trajectory of a rocket, may be implemented at thereliable level with a reliability percentage value of 100%. The reliablelevel corresponds to a highest reliability level for the adaptivereliability protocol system 100, which may guarantee a 100% PDR from theWSN 114 to the base station 102. The reliable level can also beimplemented in non-time-sensitive applications where ensuring that allof the sensor data is received may have a higher priority thantransmitting the sensor data within a predetermined period of time. Whenthe reliable level is implemented, the base station 102 and WSN 114 usenegative acknowledgement (NACK) to ensure all data is received and alsoreduce processing overhead when compared with other methods of protocolmessage acknowledgement.

At step S208, if it is determined that the reliability level for the WSN114 is not the reliable level, best effort operations are implemented atthe WSN 114. In some implementations, the best effort reliability levelcorresponds to a reliability percentage value 0%, which can bedetermined at step S202. In some implementations, the best effortoperations are employed for applications of the WSN 114 with a lowestrate of change and/or lowest criticality level. For example, WSNsassociated with monitoring slow-changing environmental conditions, suchas water levels in a lake or river may be implemented at the best effortlevel with a reliability percentage value of 0%. The best effort levelcan also be implemented in time-sensitive applications wheretransmitting the sensor data within a predetermined period of time has ahigher priority than ensuring that all of the sensor data is received.The best effort level corresponds to a lowest reliability level for theadaptive reliability protocol system 100, which may guarantee a 0% PDRfrom the WSN 114 to the base station 102. When the best effort level isimplemented, no acknowledgements are used between the base station 102and the WSN 114, and hence calculations and/or buffering at the basestation and/or WSN 114 may not be performed, which reduces an amount ofprocessing overhead.

FIG. 3 is an exemplary illustration of a round period 300, according tocertain embodiments. When the adaptive reliability process of step S212is employed, the processing circuitry of the base station 102 monitorsthe system reliability by measuring the PDR for the sensor data receivedfrom the WSN 114 over a first predetermined time interval, which canalso be referred to as a round. Each round period 300 can have apredetermined time length and is separated from a preceding andsubsequent round period 300 by a second predetermined time interval (TI)304. In some implementations, the round period 300 is associated with apredetermined amount of data. The processing circuitry of the basestation 102 can determine the length of the round period 300 and the TI304 based on the data characteristics and/or performance specificationsof the WSN 114, the type of sensor application, network stability, andthe like. For example, the processing circuitry may increase the lengthof the round period 300 when the network stability of the WSN 114decreases, which may be indicated by erratic PDR measurements that havea variance greater than a predetermined threshold. In addition, theprocessing circuitry may decrease the length of the time between roundperiods (TI) 304 as the network stability of the WSN 114 decreases.

The round period 300 also includes an assurance time period (ATI) 302corresponding to a termination of the round period 300. In someimplementations, the ATI 302 indicates to the processing circuitry thatall of the packets associated with the round period 300 have beenreceived. For example, each packet that is transmitted within the roundperiod 300 is assigned a packet serial number (PSN), and a PSNassociated with a most recently received packet is referred to as a lastpacket serial number (LPSN). Receiving the ATI 302 at the end of theround period 300 indicates to the processing circuitry of the basestation 102 that all of the packets with PSNs less than the LPSN havebeen received. In some implementations, the processing circuitry of thebase station 102 can identify the ATI 302 at the end of the round period302 by a predetermined ATI bit in a message that is set when the ATI 302is transmitted. The ATI 302 can improve efficiency of a round packetallocation process described further herein because the base station 102and WSN 114 may not need to exchange multiple messages to determine thatthe end of the round period 302 has occurred.

FIG. 4 is an exemplary flowchart of an adaptive reliability process ofstep S212 of the reliability level determination process 200, accordingto certain embodiments. When the WSN 114 is operating at the adaptivereliability level, the processing circuitry of the base station 102 usesthe PDR calculated for at least one round period 300 to determinewhether the adaptive reliability protocol system 100 operates in a besteffort mode or a reliable mode. Operations in the best effort mode andthe reliable mode correspond to how the adaptive reliability protocolsystem 100 operates at the best effort reliability level and thereliable reliability level as described previously. In otherimplementations, the adaptive reliability process S212 can also beperformed at the WSN 114.

The processing circuitry of the base station 102 controls the switchingbetween the best effort mode and the reliable mode as the PDR for theWSN 114 changes over time. The switching between the best effort modeand the reliable mode is based on an upper PDR threshold and lower PDRthreshold. For example, if the WSN 114 is operating in the best effortmode, and the PDR is less than a lower threshold, the processingcircuitry of the base station 102 can issue a control signal to switch acurrent operation mode to the reliable mode. Likewise, if the WSN 114 isoperating in the reliable mode, and the PDR is greater than an upperthreshold, then the processing circuitry can issue a control signalswitch the current operation mode to the best effort mode. Detailsregarding determining the upper PDR threshold and the lower PDRthreshold are discussed further herein. By implementing the adaptivereliability process, the processing overhead for the WSN 114 can bereduced by increasing or decreasing the reliability in response todynamic network conditions.

At step S402, the processing circuitry of the base station 10 commencesprocessing of a scheduled round. In some implementations, the scheduledround can also be interchangeably referred to as a current round. Eachround period 300 can have a predetermined time length and is separatedfrom a preceding and subsequent round period 300 by a secondpredetermined time interval (TI) 304. In some implementations, the roundperiod 300 is associated with a predetermined amount of data.

At step S404, the processing circuitry performs a round packetallocation process. In some implementations, the round packet allocationprocess includes processing packet serial numbers (PSNs) associated withreceived packets during the round period 300 in order to determine anumber of received packets and a number of dropped packets per round.Details regarding the round packet allocation process are discussedfurther herein.

At step S406, the processing circuitry of the base station 102calculates the PDR for the current round based on the number of receivedpackets and dropped packets determined during the round packetallocation process of step S404. For example, the PDR can be calculatedaccording to the equation:

${{PDR} = {\frac{R}{R + D}(\%)}},$where R indicates a number of received packets during the round period300, and D represents a number of dropped packets during the roundperiod 300. In certain embodiments, performance metrics other than thePDR can be calculated to determine whether the WSN 114 operates in thebest effort mode or the reliable mode.

At step S408, the processing circuitry of the base station 102determines whether a mode bit in a message header corresponds to besteffort operations. In some implementations, a message header of amessage sent between the base station 102 and the WSN 114 can include amode bit indicating whether the best effort mode, reliable mode, orswitching mode is in effect. If the mode bit corresponds to best effortoperations, resulting in a “yes” at step S408, then step S410 isperformed. Otherwise, if the mode bit does not correspond to best effortoperations, resulting in a “no” at step S408, then step S412 isperformed.

At step S410, if the mode bit corresponds to the best effort operations,the processing circuitry compares the PDR to a lower threshold todetermine if the PDR is less than the lower threshold. If the WSN 114 isoperating in the best effort mode and the PDR is less than the lowerthreshold, the PDR may increase when the reliable mode is implemented.If the PDR is less than the lower threshold, resulting in a “yes” atstep S410, then step S414 is performed. Otherwise, if the PDR is greaterthan or equal to the lower threshold, resulting in a “no” at step S410,then the adaptive reliability process proceeds to step S402 to commencethe next schedule round.

At step S412, if the mode bit does not correspond to the best effortoperations, meaning that the mode bit corresponds to reliableoperations, the processing circuitry compares the PDR to an upperthreshold to determine if the PDR is greater than the upper threshold.For example, if the WSN is operating in the reliable mode and the PDR isgreater than an upper threshold, the WSN 114 may be able to accommodateoperating in the best effort mode while still maintaining the PDR thatis greater than the reliability percentage value. Operating in the besteffort mode can reduce an amount of processing overhead for the WSN 114.If the PDR is greater than the upper threshold, resulting in a “yes” atstep S412, then step S414 is performed. Otherwise, if the PDR is lessthan or equal to the upper threshold, resulting in a “no” at step S410,then the adaptive reliability process proceeds to step S402 to commencethe next schedule round.

At step S414, the processing circuitry issues a switch mode message tothe WSN 114 to switch from the best effort operations to the reliableoperations, or vice-versa. When the current operation mode is thereliable mode 604, and the processing circuitry determines that the PDRis greater than the upper threshold, the processing circuitry of thebase station 102 issues a switch mode message and modifies the mode bitin the message header to switch to the best effort mode 602. When thecurrent operation mode is the best effort mode 602, and the processingcircuitry determines that the PDR is less than the lower threshold, theprocessing circuitry of the base station 102 issues a switch modemessage and modifies the mode bit in the message header to switch to thereliable mode 604.

FIG. 5 is an exemplary flowchart of a round packet allocation process ofstep S404 of the adaptive reliability process, according to certainembodiments. In some implementations, the round packet allocationprocess includes processing packet serial numbers (PSNs) associated withreceived packets during the round period 300 in order to determine anumber of received packets and a number of dropped packets per round.

At step S502, when the round packet allocation process commences, theprocessing circuitry of the base station sets a received packet countfor the round to zero and a dropped packet count for the round to zero.At step S504, when the processing circuitry of the base station receivesa sensor data packet from the WSN 114, the processing circuitryidentifies the packet serial number (PSN) associated with the sensordata packet. According to certain embodiments, the PSN is a uniqueidentification number or code associated with each data packettransmitted by the WSN 114. The PSNs for subsequent data packets may besequentially numbered so that later-transmitted data packets have higherPSNs than earlier-transmitted data packets. For example, the PSN may beincremented by a value of one for each consecutive data packettransmitted by the WSN 114.

At step S506, the processing circuitry determines whether a current PSNis equal to the last PSN (LPSN) incremented by a value of one (LPSN+1),which can indicate that a packet was not dropped between receiving thelast packet and receiving the current packet. If the current PSN is notequal to the LPSN+1, then a packet may have been dropped or anotherpreviously transmitted packet may have been received. If the current PSNis equal to the LPSN+1, resulting in a “yes” at step S506, then stepS508 is performed. Otherwise, if the PSN is not equal to the LPSN+1,resulting in a “no” at step S506, then step S510 is performed.

At step S508, if the current PSN is equal to the LPSN+1, then theprocessing circuitry of the base station 102 increments the receivedpacket count by one. In addition, the processing circuitry also sets theLPSN equal to the PSN in preparation for commencing a subsequentiteration of the round packet allocation process.

At step S510, if the current PSN is not equal to the LPSN+1, then theprocessing circuitry of the base station 102 determines whether thecurrent PSN is greater than the LPSN+1. For example, a packet of sensordata transmitted from the WSN 114 may have been dropped if the currentPSN is greater than the LPSN+1. If the current PSN is not equal to theLPSN+1, then the current PSN may correspond to a previously transmitteddata packet that is received by the processing circuitry of the basestation 102 out of sequential order. If the current PSN is greater thanthe LPSN+1, resulting in a “yes” at step S510, then step S514 isperformed. Otherwise, if the PSN is not greater than the LPSN+1,resulting in a “no” at step S510, then step S512 is performed.

At step S514, if the current PSN is greater than the LPSN+1, then theprocessing circuitry of the base station 102 increments the receivedpacket count by one and also increments the dropped packet count by one.In addition, the processing circuitry also sets the LPSN equal to thePSN in preparation for commencing a subsequent iteration of the roundpacket allocation process.

At step S512, if the current PSN is not greater than the LPSN+1, thenthe processing circuitry of the base station 102 increments the receivedpacket count by one and decrements the dropped packet count by one. Ifthe current PSN is not equal to the LPSN+1, then the current PSN maycorrespond to a previously transmitted data packet that is received bythe processing circuitry of the base station 102 out of sequentialorder.

At step S516, the processing circuitry of the base station 102determines whether the round period 300 has expired. In someimplementations, the processing circuitry determines a predeterminedlength for the round period 300 that can be based on the performancespecifications of the WSN 114, the type of sensor application, networkstability, and the like. In some implementations, the processingcircuitry initiates a timer when the round allocation process commencesfor an individual round to measure an amount of elapsed time for thecurrent round. If the amount of time that has elapsed for the currentround is greater than or equal to the round period, resulting in a “yes”at step S516, then step S518 is performed. Otherwise, if the amount oftime that has elapsed for the current round is less than the roundperiod, resulting in a “no” at step S516, then the round allocationprocess proceeds to step S504 to identify the PSN associated with asubsequently received data packet from the WSN 114.

At step S518, the processing circuitry of the base station verifies thatthe ATI 302 of the round period 300 has been received. Receiving the ATI302 at the end of the round period 300 indicates to the processingcircuitry of the base station 102 that all of the packets with PSNs lessthan the LPSN have been received. In some implementations, theprocessing circuitry of the base station 102 can identify the ATI 302 atthe end of the round period 302 by a predetermined ATI bit that is setwhen the ATI 302 is transmitted.

FIG. 6 is an exemplary illustration of adaptive reliability operationregions 600, according to certain embodiments. The adaptive reliabilityoperation regions 600 include a best effort mode 602, a reliable mode604, and a switching mode 606. When the adaptive reliability level is ineffect, the adaptive reliability protocol system 100 operates in one ofthree operation regions based on the PDR calculated for the round period300 as previously discussed. The processing circuitry of the basestation 102 determines one or more PDR thresholds that are used todetermine which operation mode is in effect. For example, the processingcircuitry can determine an upper PDR threshold (Uth) that is used todetermine when to switch from the reliable mode to the best effort mode.When the current operation mode is the reliable mode 604, and theprocessing circuitry determines that the PDR is greater than the upperthreshold, the processing circuitry of the base station 102 issues aswitch mode message and modifies the mode bit in the message header toswitch to the best effort mode 602. When the current operation mode isthe best effort mode 602, and the processing circuitry determines thatthe PDR is less than the lower threshold, the processing circuitry ofthe base station 102 issues a switch mode message and modifies the modebit in the message header to switch to the reliable mode 604.

According to certain embodiments, the switching mode 606 is a regionbounded by the upper PDR threshold and the lower PDR threshold whichindicates instances where the WSN 114 is switching between the reliablemode 604 and the best effort mode 602. For example, the base station 102and WSN 114 operate in the switching mode when a current operation modeis the best effort mode and the PDR is less than the lower PDRthreshold. In addition, the base station 102 and WSN 114 operate in theswitching mode when a current operation mode is the reliable mode andthe PDR is greater than the upper PDR threshold.

In some implementations, the processing circuitry of the base station102 determines the upper PDR threshold and lower PDR threshold during aninitialization process for the WSN 114. For example, the upper and lowerPDR thresholds may be based on the reliability percentage value. In oneexample, the processing circuitry sets the lower PDR threshold equal tothe reliability percentage value and sets the upper PDR threshold equalto a predetermined percent higher than the lower PDR threshold value.For example, if the reliability percentage value is equal to 90%, theprocessing circuitry may set the lower PDR threshold equal to 90%, andthe upper PDR threshold equal to 95%. The processing circuitry may alsoset the upper PDR threshold to a value greater than the reliabilitypercentage value and the lower PDR threshold to a value less than thereliability percentage value.

A predetermined amount of separation between the lower PDR threshold andthe upper PDR threshold may be based on an amount of network instabilityassociated with the WSN 114. In some implementations, double thresholdsare used to switch back and forth between the best effort mode 602 andthe reliable mode 604 to reduce switching overhead caused by networkinstability. For example, if the network instability of the WSN 114increases the amount of switching between the reliable mode 604 and thebest effort mode 602, the processing circuitry of the base station 102may increase the predetermined amount of separation between the upperPDR threshold and the lower PDR threshold.

A hardware description of an exemplary base station 102 for performingone or more of the embodiments described herein is described withreference to FIG. 7. In addition, the hardware described by FIG. 7 canalso apply to the computer 110 as well as circuitry associated with theWSN 111. When the base station 102, computer 110, and/or WSN 114 areprogrammed to perform the processes related to video editing describedherein, the base station 102, computer 110, and/or WSN 114 becomes aspecial purpose device. Implementation of the processes of adaptivereliability protocol system 100 on the hardware described hereinimproves the efficiency of monitoring the location of pilgrims incongested areas and monitoring medical conditions of the pilgrims. Inaddition, the processes described herein can also be applied to othertypes of tracking and surveillance technologies.

The base station 102 includes a CPU 700 that perform the processesdescribed herein. The process data and instructions may be stored inmemory 702. These processes and instructions may also be stored on astorage medium disk 704 such as a hard drive (HDD) or portable storagemedium or may be stored remotely. Note that each of the functions of thedescribed embodiments may be implemented by one or more processingcircuits. A processing circuit includes a programmed processor, as aprocessor includes circuitry. A processing circuit/circuitry may alsoinclude devices such as an application specific integrated circuit(ASIC) and conventional circuit components arranged to perform therecited functions. The processing circuitry can be referred tointerchangeably as circuitry throughout the disclosure. Further, theclaimed advancements are not limited by the form of thecomputer-readable media on which the instructions of the inventiveprocess are stored. For example, the instructions may be stored on CDs,DVDs, in FLASH memory, RAM, ROM, PROM, EPROM, EEPROM, hard disk or anyother information processing device with which the base station 102communicates, such as the WSN 114 and/or the computer 110.

Further, the claimed advancements may be provided as a utilityapplication, background daemon, or component of an operating system, orcombination thereof, executing in conjunction with CPU 700 and anoperating system such as Microsoft Windows, UNIX, Solaris, LINUX, AppleMAC-OS and other systems known to those skilled in the art.

CPU 700 may be a Xenon or Core processor from Intel of America or anOpteron processor from AMD of America, or may be other processor typesthat would be recognized by one of ordinary skill in the art.Alternatively, the CPU 700 may be implemented on an FPGA, ASIC, PLD orusing discrete logic circuits, as one of ordinary skill in the art wouldrecognize. Further, CPU 700 may be implemented as multiple processorscooperatively working in parallel to perform the instructions of theinventive processes described above.

The base station 102 in FIG. 7 also includes a network controller 706,such as an Intel Ethernet PRO network interface card from IntelCorporation of America, for interfacing with network 104. As can beappreciated, the network 104 can be a public network, such as theInternet, or a private network such as an LAN or WAN network, or anycombination thereof and can also include PSTN or ISDN sub-networks. Thenetwork 104 can also be wired, such as an Ethernet network, or can bewireless such as a cellular network including EDGE, 3G and 4G wirelesscellular systems. The wireless network can also be Wi-Fi, Bluetooth, orany other wireless form of communication that is known.

The base station 102 further includes a display controller 708, such asa NVIDIA GeForce GTX or Quadro graphics adaptor from NVIDIA Corporationof America for interfacing with display 710 of the base station 102 andthe computer 110, such as an LCD monitor. A general purpose I/Ointerface 712 at the base station 102 interfaces with a keyboard and/ormouse 714 as well as a touch screen panel 716 on or separate fromdisplay 710. General purpose I/O interface 712 also connects to avariety of peripherals 718 including printers and scanners.

A sound controller 720 is also provided in the base station 102, such asSound Blaster X-Fi Titanium from Creative, to interface withspeakers/microphone 722 thereby providing sounds and/or music.

The general purpose storage controller 724 connects the storage mediumdisk 704 with communication bus 726, which may be an ISA, EISA, VESA,PCI, or similar, for interconnecting all of the components of the basestation 102. A description of the general features and functionality ofthe display 710, keyboard and/or mouse 714, as well as the displaycontroller 708, storage controller 724, network controller 706, soundcontroller 720, and general purpose I/O interface 712 is omitted hereinfor brevity as these features are known.

The exemplary circuit elements described in the context of the presentdisclosure may be replaced with other elements and structureddifferently than the examples provided herein. Moreover, circuitryconfigured to perform features described herein may be implemented inmultiple circuit units (e.g., chips), or the features may be combined incircuitry on a single chipset, as shown on FIG. 8.

FIG. 8 shows a schematic diagram of a data processing system, accordingto certain embodiments, for performing the reliability leveldetermination process 200 and/or the adaptive reliability process S212.The data processing system is an example of a computer in which code orinstructions implementing the processes of the illustrative embodimentsmay be located.

In FIG. 8, data processing system 800 employs a hub architectureincluding a north bridge and memory controller hub (NB/MCH) 825 and asouth bridge and input/output (I/O) controller hub (SB/ICH) 820. Thecentral processing unit (CPU) 830 is connected to NB/MCH 825. The NB/MCH825 also connects to the memory 845 via a memory bus, and connects tothe graphics processor 850 via an accelerated graphics port (AGP). TheNB/MCH 825 also connects to the SB/ICH 820 via an internal bus (e.g., aunified media interface or a direct media interface). The CPU Processingunit 830 may contain one or more processors and even may be implementedusing one or more heterogeneous processor systems.

For example, FIG. 9 shows one implementation of CPU 830. In oneimplementation, the instruction register 938 retrieves instructions fromthe fast memory 940. At least part of these instructions are fetchedfrom the instruction register 938 by the control logic 936 andinterpreted according to the instruction set architecture of the CPU830. Part of the instructions can also be directed to the register 932.In one implementation the instructions are decoded according to ahardwired method, and in another implementation the instructions aredecoded according a microprogram that translates instructions into setsof CPU configuration signals that are applied sequentially over multipleclock pulses. After fetching and decoding the instructions, theinstructions are executed using the arithmetic logic unit (ALU) 934 thatloads values from the register 932 and performs logical and mathematicaloperations on the loaded values according to the instructions. Theresults from these operations can be feedback into the register and/orstored in the fast memory 940. According to certain implementations, theinstruction set architecture of the CPU 830 can use a reducedinstruction set architecture, a complex instruction set architecture, avector processor architecture, a very large instruction wordarchitecture. Furthermore, the CPU 830 can be based on the Von Neumanmodel or the Harvard model. The CPU 830 can be a digital signalprocessor, an FPGA, an ASIC, a PLA, a PLD, or a CPLD. Further, the CPU830 can be an x86 processor by Intel or by AMD; an ARM processor, aPower architecture processor by, e.g., IBM; a SPARC architectureprocessor by Sun Microsystems or by Oracle; or other known CPUarchitecture.

Referring again to FIG. 8, the data processing system 800 can includethat the SB/ICH 820 is coupled through a system bus to an I/O Bus, aread only memory (ROM) 856, universal serial bus (USB) port 864, a flashbinary input/output system (BIOS) 868, and a graphics controller 858.PCI/PCIe devices can also be coupled to SB/ICH YYY through a PCI bus968.

The PCI devices may include, for example, Ethernet adapters, add-incards, and PC cards for notebook computers. The Hard disk drive 860 andCD-ROM 866 can use, for example, an integrated drive electronics (IDE)or serial advanced technology attachment (SATA) interface. In oneimplementation the I/O bus can include a super I/O (SIO) device.

Further, the hard disk drive (HDD) 860 and optical drive 866 can also becoupled to the SB/ICH 820 through a system bus. In one implementation, akeyboard 870, a mouse 872, a parallel port 878, and a serial port 876can be connected to the system bust through the I/O bus. Otherperipherals and devices that can be connected to the SB/ICH 820 using amass storage controller such as SATA or PATA, an Ethernet port, an ISAbus, a LPC bridge, SMBus, a DMA controller, and an Audio Codec.

Moreover, the present disclosure is not limited to the specific circuitelements described herein, nor is the present disclosure limited to thespecific sizing and classification of these elements. For example, theskilled artisan will appreciate that the circuitry described herein maybe adapted based on changes on battery sizing and chemistry, or based onthe requirements of the intended back-up load to be powered.

The functions and features described herein may also be executed byvarious distributed components of a system. For example, one or moreprocessors may execute these system functions, wherein the processorsare distributed across multiple components communicating in a network.The distributed components may include one or more client and servermachines, which may share processing in addition to various humaninterface and communication devices (e.g., display monitors, smartphones, tablets, personal digital assistants (PDAs)). The network may bea private network, such as a LAN or WAN, or may be a public network,such as the Internet. Input to the system may be received via directuser input and received remotely either in real-time or as a batchprocess. Additionally, some implementations may be performed on modulesor hardware not identical to those described. Accordingly, otherimplementations are within the scope that may be claimed.

The above-described hardware description is a non-limiting example ofcorresponding structure for performing the functionality describedherein. In other alternate embodiments, processing features according tothe present disclosure may be implemented and commercialized ashardware, a software solution, or a combination thereof. Moreover,instructions corresponding to the reliability level determinationprocess 200 and/or the adaptive reliability process S212 in accordancewith the present disclosure could be stored in a thumb drive that hostsa secure process.

According to certain embodiments, the adaptive reliability protocolsystem 100 provides the processing power to adaptively modify theoperation mode of the WSN 114 between the best effort mode and thereliable mode based on the calculated PDR for one or more round periodsin order to conserve processing resources of the WSN 114. The processesdescribed herein can also be applied to other technical fields thatinvolve adapting other types of communication networks to dynamicallychanging environments. In some embodiments, WSNs may have limitedmemory, bandwidth, and energy resources, and operating the WSN 144 abovea predetermined reliability threshold may result in a processingoverhead that may exceed the processing capabilities of the WSN 114.Providing the adaptive QoS protocol for the WSN 114 via the processesdescribed herein can increase processing efficiency while maintaining apredetermined PDR.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of this disclosure. For example, preferableresults may be achieved if the steps of the disclosed techniques wereperformed in a different sequence, if components in the disclosedsystems were combined in a different manner, or if the components werereplaced or supplemented by other components. The functions, processesand algorithms described herein may be performed in hardware or softwareexecuted by hardware, including computer processors and/or programmablecircuits configured to execute program code and/or computer instructionsto execute the functions, processes and algorithms described herein.Additionally, an implementation may be performed on modules or hardwarenot identical to those described. Accordingly, other implementations arewithin the scope that may be claimed.

The invention claimed is:
 1. A device comprising: processing circuitryconfigured to determine a reliability level for a communication network,determine a packet delivery ratio (PDR) for a round period of thecommunication network operating at reliability level based on a packetserial number (PSN), the round period being a predetermined period formeasuring the PDR of sensor data received from the communicationnetwork, control the communication network to operate in an adaptivereliability mode in response to the reliability level being within apredetermined range, the adaptive reliability mode including a besteffort mode, a reliable mode, and a switching mode based on the PDR,wherein the processing circuitry is further configured to controloperation of the communication network to operate in the best effortmode in response to the PDR being greater than an upper PDR threshold,control operation of the communication network to operate in thereliable mode in response to the PDR is less than a lower PDR threshold,and control operation of the communication network to operate in theswitching mode when transitioning between the best effort mode and thereliable mode, the control including issuing a switch mode messageincluding a modified mode bit in the message header, and detect anassurance time interval (ATI) corresponding to a termination of theround period.
 2. The device of claim 1, wherein the communicationnetwork is a wireless sensor network.
 3. The device of claim 1, whereinthe processing circuitry is further configured to determine a timelength for the round period based on data characteristics of thecommunication network, the data characteristics including reliabilityperformance specifications.
 4. The device of claim 3, wherein theprocessing circuitry is further configured to determine an amount oftime between successive round periods based on the data characteristicsof the communication network.
 5. The device of claim 1, wherein theprocessing circuitry is further configured to detect a dropped packetwhen a current PSN is greater than a last PSN plus one.
 6. The device ofclaim 1, wherein the processing circuitry is further configured todetermine the reliability level and an associated reliability percentagevalue for the communication network based on at rate of change of sensorvalues of one or more sensor devices associated with the communicationnetwork.
 7. The device of claim 1, wherein the processing circuitry isfurther configured to determine an upper PDR threshold and lower PDRthreshold based on the reliability percentage value.
 8. The device ofclaim 7, wherein the processing circuitry is further configured todynamically update the upper PDR threshold and lower PDR threshold basedon network conditions.
 9. The device of claim 1, wherein the processingcircuitry is further configured to perform negative-acknowledgement(NACK) messaging in the reliable mode.
 10. The device of claim 1,wherein the processing circuitry is further configured to operate in theswitching mode when a current operation mode is the best effort mode andthe PDR is less than a lower PDR threshold.
 11. The device of claim 1,wherein the processing circuitry is further configured to operate in theswitching mode when a current operation mode is the reliable mode andthe PDR is greater than an upper PDR threshold.
 12. The device of claim1, wherein the processing circuitry is further configured to modify anoperation mode of the communication network via a mode bit.
 13. Thedevice of claim 1, wherein the processing circuitry is furtherconfigured to operate in an application layer independent from a mediaaccess control (MAC) layer.
 14. A method comprising: determining, via aserver, a reliability level for a communication network; determining,via the server, a packet delivery ratio (PDR) for a round period of thecommunication network operating at reliability level based on a packetserial number (PSN), the round period being a predetermined period formeasuring the PDR of sensor data received from the communicationnetwork; controlling, via the server, the communication network tooperate in an adaptive reliability mode in response to the reliabilitylevel being within a predetermined range, the adaptive reliability modeincluding a best effort mode, a reliable mode, and a switching modebased on the PDR; the controlling further comprising: controllingoperation of the communication network to operate in the best effortmode in response to the PDR being greater than an upper PDR threshold,controlling operation of the communication network to operate in thereliable mode in response to the PDR is less than a lower PDR threshold,and controlling operation of the communication network to operate in theswitching mode when transitioning between the best effort mode and thereliable mode, the control including issuing a switch mode messageincluding a modified mode bit in the message header, and detecting anassurance time interval (ATI) corresponding to a termination of theround period.
 15. A non-transitory computer readable medium havinginstructions stored therein that, when executed by one or moreprocessor, cause the one or more processors to perform a method ofadaptively controlling a reliability protocol, the method comprising:determining, via a server, a reliability level for a communicationnetwork; determining, via the server, a packet delivery ratio (PDR) fora round period of the communication network operating at reliabilitylevel based on a packet serial number (PSN), the round period being apredetermined period for measuring the PDR of sensor data received fromthe communication network; controlling, via the server, thecommunication network to operate in an adaptive reliability mode inresponse to the reliability level being within a predetermined range,the adaptive reliability anode including a best effort mode, a reliablemode, and a switching mode based on the PDR; the controlling furthercomprising: controlling operation of the communication network tooperate in the best effort mode in response to the PDR being greaterthan an upper PDR threshold, controlling operation of the communicationnetwork to operate in the reliable mode in response to the PDR is lessthan a lower PDR threshold, and controlling operation of thecommunication network to operate in the switching mode whentransitioning between the best effort mode and the reliable mode, thecontrol including issuing a switch mode message including a modifiedmode bit in the message header, and detecting an assurance time interval(ATI) corresponding to a termination of the round period.
 16. The deviceof claim 1, wherein the circuitry detects the ATI by PSN to be a lastpacket serial number (LPSN).